repro steps:
- create a class diagram
- create and name a few elements on the diagram (so you can tell it's the same
diagram)
- rename the class diagram to a different name from the project tree
- click on anywhere in the class diagram to show in the Navigator window again
Result: the Navigator window title still shows the original class diagram name,
even though you switch to other open diagrams (if any) and then switch back to
the renamed diagram.

Workaround: click on any element in the diagram and then on the diagram again to
see the new name.